Power tool

ABSTRACT

A portable power tool having two work implements, such as a drill bit and a screwdriver bit, located at opposite ends of the body of the tool and facing in opposite directions with the body being mounted on a handle so that it can be turned through 180* relative to the handle to bring one or the other of the implements into a working position. The body is provided with guard means so that whichever implement is not working is covered by the guard means. An air motor for driving the work implements may be mounted in the body of the tool or in the handle and driving the work implements through suitable gearing.

o United States Patent 1 1 [111 3,783,955 Gill 1 Jan. 8, 1974 POWER TOOL2,229,951 1/1941 West et a1 173/48 x 1751 1mm Peter o Wolverhampton,3232332 12/1323 "11351 3 England 3,034,550 5/1962 Dahl 7/15 x [73]Assignee: G.K.N. Screws & Fasteners Limited,

wofley, England Primary ExaminerErnest R. Purser 22 i 21 1972Att0rneyJOhn W. Malley et al.

App]. No.2 246,271

Lebus 51/128 X [57] ABSTRACT A portable power tool having two workimplements, such as a drill bit and a screwdriver bit, located atupposite ends of the body of the tool and facing in opposite directionswith the body being mounted on a handle so that it can be turned throughl80relative to the handle to bring one or the other of the implementsinto a working position. The body is provided with guard means so thatwhichever implement is not working is covered by the guard means. An airmotor for driving the work implements may be mounted in the body of thetool or in the handle and driving the work implements through suitablegearing.

14 Claims, 8 Drawing Figures SHEET 1 OF 4 :EEEEzzEz:

PATENTEI] JAN 81974 PATENTEDJAN 8 m4 SHEET [1F 5 8 N0 5 mm vs no mm mmmm mm EON 3 R3 cm R R 1 POWER TOOL FIELD OF THE INVENTION This inventionrelates to portable power tools (such as for example, drills,screwdrivers, rivet applicators).

BACKGROUND OF THE INVENTION The broad object of the invention is toprovide a new or improved power tool having a pair of holders fordifferent types or sizes of work implement whereby a selected implementcan be used as desired followed by change over to another type or sizeof implement without having to remove one implement and replace it inits holder with another one as is the case with the generally knownconventional forms of power tools which have only one holder for theworking implement. For example, with a conventional electric drill whenit is desired to perform a drilling operation followed by acountersinking operation the working implement, namely the drill bit,has to be changed for a different type of Working implement namely thecountersinking bit after the hole has been drilled. In other cases it issometimes preferred to use two separate tools such as for example in theinserting of self tapping screws where one tool is used to drill thehole and another tool is used to insert the screw.

SUMMARY OF THE INVENTION According to the invention there is provided apower tool comprising a body, two holders for work implements mounted inor on said body in opposed relationship so that the implement in oneholder is presented in a direction directly opposite to the direction inwhich the implement in the other holder is presented, power means in oron the body for supplying the motive power to each of the holders, guardmeans on the body for effectively guarding the implement not in use whenthe other implement is being used and means for moving the holdersrelatively to the guard means to bring one of the holders into itsoperating position while the other holder is in a position where itsimplement is within the region of protection of the guard means.

For a portable hand tool a preferred form of power means is a generallyknown form of air motor which is driven from a source of compressed airand which can be easily housed within the body of the tool or within ahandle projecting from the body.

Using such an air motor, in one form of tool in accordance with theinvention the body is of generally cylindrical configuration and has ahandle projecting transversely frome one side thereof, the handle alsobeing of a generally cylindrical form and providing a housing for theaccommodation of the air motor and its associated gearing. The outputshaft from the air motor may project into the body of the tool and thework implement holders may be mounted on either side of said poweroutput shaft so as to be directly aligned within the body and eachholder may have a rotary shaft for supplying the motive power to itswork implement and conveniently the two shafts may be arranged in axialalignment and may both be driven directly by suitable gearing from theoutput shaft of the air motor.

With this arrangement the body may comprise an outer casing which at itsends includes guard means for the work implements and an inner casingwithin which inner casing the aforesaid holders are mounted, thearrangement being that the outer casing is slidable upon the innercasing so that when relative sliding movement takes place between theouter and inner casings in one direction one of the work implements isprojected beyond its associated guard means and the other work implementis withdrawn within its associated guard means.

Conveniently, the handle which houses the air motor is also ofcylindrical form and is arranged so as to project at right angles fromthebody and rack and pinion form of gearing may be provided between theouter housing of the handle and the outer casing of the body wherebyrotation of the outer casing of the body relative to the outer housingof the handle causes an axial displacement of the outer casing of thebody relatively to the inner casing thereof thus causing movement of therespective guard means in relation to the work implements guardedthereby.

In another embodiment according to the invention an air motor fordriving the shafts of both work holders may be mounted within agenerally cylindrical body which itself is mounted for rotation upon ahandle about an axis at right angles to the axis of the cylindrical bodyand the handle may have fixed thereon a projecting guard means, thearrangement being that the body may be swung through so as to bring onework implement out of the region and protection of the guard means intoan operating position whilst moving the other work implement back intothe region of'protection of the guard means.

In a further embodiment according to the invention the body may be ofgenerally cylindrical form, housing a motor and gearing for driving theholder arranged in axial alignment, the body being mounted for rotationupon a handle about an axis at right angles to the axis of thecylindrical body and there being provided at each end of the body atwo-part guard comprising a first sleeve fixed to the body and a secondsleeve telescopically engaged with the first sleeve so as to be movablebetween a fully extended position in which it guards its associated workimplement and a retracted position in which it exposes the implement.

BRIEF DESCRIPTION OF THE DRAWINGS The invention is illustrated in theaccompanying drawings wherein:

FIG. 1 is a view in section in side elevation of one form of tool,

FIG. 2 is a section on the line 2--2 of FIG. 1,

FIG. 3 is a section on the line 33 of FIG. 1,

FIG. 4 is a view to a smaller scale of the complete tool in sideelevation,

FIG. 5 is a view in side elevation of another form of tool,

FIG. 6 is a scrap plan view of the one end of the tool,

FIG. 7 is a sectional view in side elevation of another form of tool,and

FIG. 8 is a scrap plan view of one end of the tool.

DESCRIPTION OF PREFERRED EMBODIMENTS The form of tool shown in FIGS.l-to 4 of the drawings is one suitable for accommodating two rotary workimplements such as, for example, a drill for drilling a hole in metalsheet and a screwdriver bit for driving a self-tapping screw into suchdrilled hole.

The body of the tool comprises the outer casing 10 which at each end hasscrewed thereon the guard means indicating at 11 and 12. The outercasing is of generally cylindrical form with the outer end portions ofthe guards members 11 and 12 being tapered to generally frusto-conicalform and each having an open end through which the associated w'orkimplement can project. The body further comprises a cylindrical innercasing 13 and the arrangement is such that the outer casing can slidefreely in the axial direction upon the inner casing 13.

Projecting at right angles to the axis of the body at one side thereofis a handle generally indicated at 14 and comprising an outercylindrical housing 15 within which is housed a known form of air motorwith its associated gearing indicated at 16. The output shaft 17 fromthe air motor 16 projects through an opening into the space within theinner casing 13 and has fixed thereon a first bevel gear 18 and a secondbevel gear 19.

The body comprising outer casing 10 and inner casing 13 can rotaterelative to the handle about the central axis of outer housing 15. Fixedto the outer housing 15 of the handle is a gear wheel 20 and this mesheswith a toothed rack 21 which is fixed to the outer casing 10 of thebody.

Two work implement holders 22 and 23 are mounted fixedly within theinner casing 13 and each has rotatably mounted therein its appropriatedriving shaft for providing the rotary motion required to operate itsassociated work element and in the particular example shown the holder22 is the type adapted to take a drill bit 24 whilst the holder 23 isthe type adapted to take a screwdriver bit 25, the screwdriver bit beingspring loaded axially in known manner so that it is not con nected toits rotary drive shaft until axial pressure has been applied to engagethe screwdriver bit with a screw whereupon the screwdriver bit movesaxially against the spring pressure and the drive is connected from itsdrive shaft.

The drive shaft of holder 22 has a bevel gear 26 fixed at its inner endand in mesh with the bevel gear 19 on the output shaft 17 from the airmotor and the drive shaft of holder 23 has a bevel gear 27 at its innerend and in mesh with the other bevel gear 18 on the output shaft fromthe air motor.

The arrangement of the gearing is such that the gearing 19, 26, providesa high speed drive to the drill bit whereas the gearing 18, 27 providesa reduced speed drive to the screwdriver bit.

The position of the tool as shown in FIG. 1 is for the operation of thedrill bit with the gear 20 along at the left hand end of the rack 21, asseen in the drawing, with the result that the outer casing 10 has beenslidden to the right, as seen in the drawing, so as to bring the guard11 back and clear of the drill bit 24 which is projecting from the openend of the guard. Conversely, with the gear 20 at the extreme right handend of the rack 21 the guard 12 would be drawn back and the screwdriverbit would be projecting from the open end of the guard 12 (as shown inFIG. 4.).

In practice, therefore, by holding the outer housing 15 of the handlestationary and by turning the outer casing of the body through 180 aboutthe vertical axis of the handle, the rack and pinion gearing 20, 21causes relative movement between the inner and outer casings of the bodyand thus a movement of the outer casing 10 between the limits imposed bythe length of the rack 21 to expose one or the other of the workimplements of the tool.

Trigger means for operating the tool and also providing a form of safetylock are shown in FIGS. 1 to 4 and hereinafter described.

By means of a suitable adapter 8 an air hose can be connected to thelower end of the handle 14 and within the end portion 28 of the airmotor there is provided a valve mechanism for controlling the supply ofcompressed air to the motor. (see FIG. 3).

A trigger for operating the tool is mounted upon the handle 14 at aposition approximately just below midway between the ends of the handle,the trigger being in the form of a bar 29 which is pivotally mountedabout an axis 30 which is at right angles to the axis of the handle andthe bar extending substantially from top to bottom of the handle.

At its lower end this bar 29 engages with a U" shaped yoke 31 whichslides in the generally horizontal plane (assuming the handle to be heldvertically), between spaced apart flanges 32 on the portion 28 of theair motor and one side or the other side of this U" yoke, (depending onwhether the tool is set for drilling or screwdriving), is used tooperate plunger mechanism 33 for opening and closing the air inlet valve34 to the motor.

The rack 21 (see FIG. 2) is for-med upon one face of an elongatedaperture in a plate 35 which is secured to the underside of the outercasing 10 of the body. The gear 20 can travel along this aperture duringmovement from one end of the rackto the other. At each end the plate 35has a slot 36 extending in the axial direction of the body.

At its upper end the bar 29 forming the trigger has a projecting nose 37which is adapted to engage within one or the other of the aforesaid endslots 36 and the bar 29 forming the trigger is acted upon above andbelow its pivotal axis by springs 38 and 39 which are arranged tonormally hold the bar in a position in which the nose 37 at its upperend is engaging within the entrance of one of the aforesaid slots 36 andthe yoke 31 at the lower end is in a position in which the valvemechanism 33, 34 controlling the inlet of air to the motor is in theclosed position. (This position of nose 37 is shown in full lines inFIG. 2.). Thus, in this condition the tool is in a safe position withthe air to the motor cut off and the outer casing of the body 10 lockedin relation to the handle 14 so that it cannot be turned from oneposition to the other. In this position, if the trigger is now pressedat its upper end, that is the end nearest the body, then the lower endmoves away from the handle and this outwards movement of the yoke 31operates the valve mechanism to admit air to the air motor and thusdrive whichever implement is projecting from the end of the body. Whenthe trigger bar is released it moves back into the position in which theair supply is cut off and in which the nose at the top of the triggerbar is still engaging within the slot 36 so as to prevent any movementof the body in relation to the handle. During the operation of the workimplement this nose is engaged to the full extent within such slotpreventing any possibility of movement between the body and the handle.(The position of nose 37 shown in dotted lines on the right in FIG. 2.).

To change from one implement to another the trigger bar is now graspedat its lower end and pivoted so that its lower end moves in towards thehandle and its upper end outwardly so that the nose on the upper end isdisengaged from the aforesaid slot 36, (see dotted line position of nose37 on left side in .FIG. 2.), and then the outer casing can be rotatedthrough 180 to cause relative traverse between the gear 20 and rack 21to bring the other work implement into the operative condition in whichit is projecting beyond its guard. Having reached this position releaseof the trigger bar causes it to return to its neutral position in whichthe nose at the top of the trigger bar again engages in the entrance ofthe other slot 36 and locks the body from movement in relation to thehandle.

The aforesaid end slots are such that one side of the slot is longerthan the other, (see FIG. 2), the longer side thus forming a stopagainst which the nose 37 at the top of the trigger bar engages afterthere has been movement through 180 so thatthe two positionsof the bodyin relation to the handle are determined by the longer sides of theaforesaid slots.

It will be appreciated that although the example above has beendescribed in relation to two work implements having a rotary action,itis possible for appropriate mechanism to be incorporated within eitheror both of the holders 24, 25 to give a reciprocating or hammeringmotion to a work implement or a combined rotary and hammering effect canbe'obtained with generally known mechanisms.

The necessity for providing effective guard members will be appreciatedwhen it is understood that in operating the one implement, for examplethe screwdriver bit, the operator would have the tool positioned withthe other implement, namely the drill, pointing directly at his body andwould be applying axial pressure in the direction towards thescrewdriver bit so that in the event of any slip the projecting end ofthe drill, if not otherwise guarded, could cause serious injury to theoperator particularly as with the arrangement shown such drill would berotating by virtue of its connection through the gearing to thedrivefrom the air motor.

Reference is now made to FIGS. 5 and 6 which show a further embodimentof the invention, being a somewhat simpler form of tool.

ln FIGS. 5 and 6 the body 40 of the tool is of generally cylindricalform with the air motor (not shown) for providing the drive mountedwithin such body substantially at the mid position thereof and having anextension of its shaft at both ends so that one end can provide a driveto one tool holder 41 and the other end can provide a drive to the othertool holder 42 with the tool holders being mounted at opposite ends ofthe cylindrical body 40.

A pistol grip type of handle generally indicated at 43 is provided,connected to the intermediate portion 44 of the body and the body ismounted on the handle so that it can be swivelled through 180 about anaxis which is normal to its own axis upon a suitable bearing pedestal 45provided between the pistol grip handle 43 and the body portion 44.

In this embodiment a single guardmember 46 is provided which extendsfrom the handle 43 near the position of mounting between the handle andthe body and which has a part 47 which extends rearwardly of the handlefor a sufficient distance to enable its outer end to be curved upwardlyinto the form of a cup 48 in which position it provides a guard for theprojecting end of the work implement which is not being used.

The air supply to the motor is taken up through the pistol grip handleand through a generally known form of control valve and a press-buttontrigger mechanism 49 is provided on the front edge of the pistol griphandle to control operation in the normal way. A locking mechanismbetween the trigger mechanism and the body (similar to that shown inFIG. 2) is provided so that when one work implement is in the operativeposition and is in use there is no possibility of any movement takingplace between the body and the handle. A nose 50 on the triggermechanism is used to engage in one or the other of two slots 51 on theunderside of the body.

Reference is now made to FIGS. 7 and 8 which shows another embodiment ofthe invention.

The main part of the body shown at 60 is of generally cylindrical formand housesan air motor 61 and at one end the body 60 has screwed thereonan extension 62 in which is housed a high ratio reversing gear box 63driven from the driving shaft of the air motor and driving an adjustablemultiplate friction clutch 64, to which is drivingly connected theholder 65 for a screwdriver bit 66.

The other end of the shaft of theair motor drives a low rationon-reversing gear box 67, the output shaft of which drives the chuck 68into which is fitted a drill bit 69. The parts so far described arecomponents of generally known construction and the arrangement pro videsfor a high speed drive from the air motor to the chuck 68 for drillingand a low speed drive to the holder 65 for using the bit 66 forinserting screws.

The body part 60 is mounted on the upper end of a swivel tube 70 whichextends downwardly through an axial passage in a pistol grip handle 71and which swivel tube assembly contains a generally known form of airvalve mechanism generally indicated at 72. The whole of the assembly ofswivel tube'and valve mechanism 70 and 72 is rotatably mounted in thepistol grip handle 71 so that the body 60 being connected to the upperend of the swivel tube 70 can be turned relative to the handle 71 aboutthe axis of the tube 70. At the forward side of the handle 71 there is apress-button trigger 73 controlling a valve rod 74 for the opening andclosing of the air valve to allow admission of air to the air motor 61,the air supply being connected to the bottom end of the handle 71. v

The guard for surrounding each work implement comprises a fixed outersleeve and a movable tele- 'scopicinner sleeve and in the position shownin FIG.

outer sleeve 75 is fixed at its inner end to the body 60 v and the innersleeve is in two parts and comprises a cylindrical part 76 and connectedthereto a forward frusto-conical part 77 and as shown the forward edgeof the cylindrical part 76 projects beyond the rear end of thefrusto-conical part 77. A ring 78 is secured to the interior of theassembly of the inner sleeve and a coil spring 79 acts between this ringand the inner end of the outer sleeve 75 at the position where it isfixed to the body 60 so that the spring 79 is urging the inner sleeveassembly in the outward direction into the position in which it wouldcover and act as a guard for the drill bit 69.

shown in FIG. 7 by the engagement of the forward edge of the sleeve 76with a nose 82 which is carried at one end of a spring metal strip 83the other end of which is fixed to a U-shaped bracket 84 secured to theforward face of the pistol grip handle 71. The nose 82 has an inclinedforward edge so that as the inner sleeve assembly of the guard is pulledinto the retracted position by the finger piece 81 its innermost edgewhen engaging the forward inclined edge of the nose 82 will deflect thenose 82 radially outwardly until the inner sleeve has moved to its fullyretracted position whereupon the nose 82 can snap back into position andengage with the forward edge of the sleeve 76 to prevent the sleeve frommoving outwardly during the operation of the tool using the drill bit69. On its underside the outer sleeve 75 is provided with a rectangularslot 85 to permit, the movement of the nose 82 into and out ofengagement with the inner sleeve assembly of the guard and as will beseen from FIG. 8 the circumferential width of the slot 85 issubstantially greater than the width of the nose 82 for the purposehereinafter described.

In FIG. 8 there is shown in full lines the position of the guard whenthe drill bit is being operated and the inner sleeve assembly of theguard withdrawn wholly within the outer sleeve 75. The outer sleeve 75is also shown in dotted lines in a position in which the body 60 hasbeen turned relative to the handle 71 through a small angle to aposition in which the forward edge of the sleeve 76 has just moved outof engagement with the nose 82 so that the straint is removed from theinner sleeve assembly of the guard and it has been urged outwardly bythe spring 79 the frusto-conical part 77 of the inner guard assemblybeing shown in the extended position in chain dotted lines in FIG. 8.Hence the act of commencing to turn the body of the tool relative to thehandle 71 to'change from one working position to another automaticallyensures that the inner sleeve assembly of the telescopic guard movesinto its outer operative position in which it protects the drill bit 69and the drill bit cannot be exposed again until a deliberate action istaken to retract the inner sleeve assembly of the guard by moving thefinger piece 81 rearwardly.

In the righthand side of FIG. 7 there is shown a similar form oftelescopic guard for the driver bit 66, the guard here being shown inits operative guarding position and also there is shown means wherebythe inner sleeve of the telescopic guard is prevented from being movedinto its retracted position whilst the driver bit is in this inoperativeor out of work position. Thus, whilst the drill bit is being used,should the operator apply any pressure to the extended inner sleeve ofthe telescopic guard it cannot move inwardly and thus there is no dangerof the screwdriver bit becoming exposed and creating a hazard.

The telescopic guard for the screwdriver bit comprises an outer sleeve86 and an inner sleeve assembly 87 which has a forward part 88 ofreduced diameter so as to provide an internal shoulder and a coil spring89 acts between this internal shoulder and the position where the outersleeve 86 is connected to the body 60 so as to normally urge the innersleeve assembly into the forward protective position, as shown in FIG.7. The inner sleeve assembly is provided with a finger piece 90 workingin a slot 91 on the upper side of the outer sleeve 86 so that the innersleeve assembly can be withdrawn into its retracted position by handagainst the pressure of spring 89.

On its underside the outer sleeve 86 has a rectangular slot 92 the sameas the slot 85 in the upper guard and when the screwdriver bit is in usein the operative position the nose 82 operates through this slot 92 toengage the outer face of the shoulder 93 btween the two parts 87 and 88of the inner sleeve assembly so as to hold the inner sleeve assembly inits retracted position against the pressure of the spring 89.

The means for preventing inwards movement of the inner sleeve assembly87, 88 when it is in the position shown in FIG. 7 comprises an arm 94fixed to the upper end of the handle 71 and extending rearwardly thereofand having at its outer end an upwardly projecting lug 95 which lieswithin the slot 92 when the parts are in the position shown in FIG. 5and which provides an abutment engaged by the inner edge of inner sleeve87 thus preventing any inwards movement of inner sleeve 87 so long asthe parts are in the position shown in FIG. 7. Thus, whilst the oneworked implement is in use the inner sleeve assembly of the guard of theother implement not in use cannot be inadvertently pushed inwardly toexpose the implement and create a hazard.

It will be appreciated that when the tool-is in the reverse position tothat shown in FIG. 7 the lug 95 will operate in the same way to preventany inwards movement of the inner sleeve 76 of the other guard bysimilar engagement with the inner edge of this inner sleeve.

To prevent any movement of the body relative to the handle when one orthe other of the implements is actually in use there is provided alocking action between the trigger 73 and two slots 96 and 97 formed onthe underside of the body, such slots being diametrically opposed andeach slot having a longer side and a shorter side.

The longer sides of the slots 96 and 97 are shown in the drawing and inthe position shown the trigger 73 being in the inoperative position isjust outside the mouth of the slot 97 (i.e., it is clear of the shorterside of the slot). When the trigger 73 is pressed inwardly to operatethe air motor its upper portion enters within the slot 97 tothe fulldepth and in this position positively prevents any turning movement ofthe body 16 relative to the handle 71. The same action takes place whenthe tool is in the other position using the screwdriver bit 66 when thetrigger co-operates with the slot 96.

The upper part of the trigger also provides a locating stop when thebody 16 is swung from one position through l80 to the other when thelonger side of either slot 96 or 97 comes into engagement with the upperpart of the trigger at the end of the arc of movement, thus setting thebody of the tool in the correct position relative to the handle forwhichever implement is to be used.

I claim:

1. A power tool including an elongate body; power means; two implementholders directed in opposite directions and disposed at or adjacentopposed end por- 9 tions of the tool body and powered by said powermeans; a handle extending generally at right angles to the axis ofelongation of the body and having trigger means for selectivelyoperating said power means; and guard means arranged to guard oneimplement which is not in use while the other implement is being used,the guard means being operatively associated with the handle, the handlebeing rotatable on its own axis relative to the body of the tool betweenextreme positions in which the trigger means face towards each endportion and hence each implement respectively and the guard means beingarranged so that, when the trigger means on the handle are directedtowards one implement whereby that implement is in an operativecondition in which it is capable of being used, the guard means iseffective to guard the other implement from external contact and whenthe handle is rotated from said position prior to operating the otherimplement, the guard means is automatically moved thereby into aposition where it is effective to guard said one implement from externalcontact.

2. A power tool according to claim 1 wherein the body is of generallycylindrical form and has a handle projecting transversely from one sidethereof said handle being of generally cylindrical form and providinghousing for an air motor and gearing, the output shaft from the airmotor projecting into the body of the tool and the work implementholders being mounted in axial alignment on either side of said outputshaft and each holder having a rotary shaft for supplying power to itswork implement driven by gearing from the output shaft of the air motor.

3. A power tool according to claim 2 wherein the body comprises an outercasing which at its ends includes guard means for the work implementsand an inner casing within which inner casing the aforesaid holders aremounted, the arrangement being that the outer casing is slidable uponthe inner casing so that when relative sliding movement takes placebetween the outer and inner casings in one direction one of the workimplements is projected beyond its associated guard means and the otherwork implement is withdrawn within its associated guard means.

4. A power tool according to claim 3 wherein the handle has an outercylindrical housing arranged to project at right angles from the bodyand rack and pinion gearing is provided between the outer housing of thehandle and the outer casing of the body whereby rotation of the outercasing of the body relative to the outer housing of the handle causes anaxial displacement of the outer casing of the body relatively to theinner casing thereof thus causing movement of the respective guard meansin relation to the work implements associated therewith.

5. A power tool according to claim 4 wherein a rack is fixed to theunder side of the outer casing of the body and has meshing engagementwith a pinion fixed to the outer housing of the handle.

6. A power tool according to claim 1 wherein the body is of generallycylindrical form and houses therein a motor for driving the shafts ofboth work holders the body being mounted upon a handle for rotationabout an axis at right angles to the axis of the cylindrical body andthe handle having fixed thereon a projecting guard means, thearrangement being that the body may be rotated through 180 so as tobring one implement out of the region of protection of the guard meansinto an operating position whilst moving the other implement back intothe region of protection of the guard means.

7. A power tool according to claim 6 wherein the guard means comprisesan arm fixed at one end to a handle adjacent where the body is mountedthereon said arm extending radially outwardly from the handle and havingits outer end curved back to provide the guard for one or the other ofthe work implements.

8. A power tool according to claim 1 wherein the body is of generallycylindrical form and houses a motor and gearing for driving the holdersarranged in axial alignment, the body being mounted for rotation upon ahandle about an axis at right angles to the axis of the cylindrical bodyand there being provided at each end of the body a two-part guardcomprising a first sleeve fixed to the-body and a second sleevetelescopically engaged with the first sleeve so as to be movable betweena fully extended position in which it guards its associated workimplement and the retracted position in which it exposes the implement.

9. A power tool according to claim 8 wherein each two-part guard has thesecond sleeve slidable telescopically within the first sleeve and springurged in the direction outwardly of the first sleeve, there being fixedto the handle of the tool, at the front thereof, a resilient lockingmember which projects through the wall of the outer sleeve and engagespart of the inner sleeve, of the guard which is in the front positionfor operation of its implement, so as to hold the inner sleeve in theretracted position.

10. A power tool according to claim 9 wherein the said locking membercomprises a nose at the free end of a resilient arm the upper end ofwhich is fixed to the handle, the nose projecting through acircumferential slot in the outer sleeve and such slot being wider inthe direction transverse to the axis of the sleeve than the nose,whereby a small angular movement of the body from the operative positionresults in the said part of the inner sleeve moving out of engagementwith the nose to permit the inner sleeve to be spring urged to its outerposition.

11. A power tool according to claim 10 wherein, at its rear side, thehandle has fixed thereto a locking lug which projects through theaforesaid slot of the guard, the implement of which is in theinoperative positon, and engages a part of the inner sleeve to preventsame from being moved inwardly in relation to the outer sleeve.

12. A power tool according to claim 11 wherein the inner sleeve of eachguard has a finger piece on its wall projecting outwardly through anelongated slot in the outer sleeve whereby the inner sleeve can be movedmanually from its extended position to its retracted position.

13. A power tool according to claim 1 wherein two similar slots areprovided on the underside of the body of the tool and the trigger has apart arranged so as to engage in one or other of the slots when thetrigger is pressed to operate the motor, whereby relative movementbetween the body and the handle when the motor is driven is prevented.

14. A power tool according to claim 13 wherein each said slot has oneside edge longer than the other and an open mouth through which saidpart of the trigger engages when it is pressed to operate the motor, andsaid part of the trigger being engaged also by the longer edge of theslot when it is in the released position so as to act as a stop definingthe operative position of the body whichever work implement is in use.

=l l =l=

1. A power tool including an elongate body; power means; two implementholders directed in opposite directions and disposed at or adjacentopposed end portions of the tool body and powered by said power means; ahandle extending generally at right angles to the axis of elongation ofthe body and having trigger means for selectively operating said powermeans; and guard means arranged to guard one implement which is not inuse while the other implement is being used, the guard means beingoperatively associated with the handle, the handle being rotatable onits own axis relative to the body of the tool between extreme positionsin which the trigger means face towards each end portion and hence eachimplement respectively and the guard means being arranged so that, whenthe trigger means on the handle are directed towards one implementwhereby that implement is in an operative condition in which it iscapable of being used, the guard means is effective to guard the otherimplement from external contact and when the handle is rotated from saidposition prior to operating the other implement, the guard means isautomatically moved thereby into a position where it is effective toguard said one implement from external contact.
 2. A power toolaccording to claim 1 wherein the body is of generally cylindrical formand has a handle projecting transversely from one side thereof saidhandle being of generally cylindrical form and providing housing for anair motor and gearing, the output shaft from the air motor projectinginto the body of the tool and the work implement holders being mountedin axial alignment on either side of said output shaft and each holderhaving a rotary shaft for supplying power to its work implement drivenby gearing from the output shaft of the air motor.
 3. A power toolaccording to claim 2 wherein the body comprises an outer casing which atits ends includes guard means for the work implements and an innercasing within which inner casing the aforesaid holders are mounted, thearrangement being that the outer casing is slidable upon the innercasing so that when relative sliding movement takes place between theouter and inner casings in one direction one of the work implements isprojected beyond its associated guard means and the other work implementis withdrawn within its associated guard means.
 4. A power toolaccording to claim 3 wherein the handle has an outer cylindrical housingarranged to project at right angles from the body and rack and piniongearing is provided between the outer housing of the handle and theouter casing of the body whereby rotation of the outer casing of thebody relative to the outer housing of the handle causes an axialdisplacement of the outer casing of the body relatively to the innercasing thereof thus causing movement of the respective guard means inrelation to the work implements associated therewith.
 5. A power toolaccording to claim 4 wherein a rack is fixed to the under side of theouter casing of the body and has meshing engagement with a pinion fixedto the outer housing of the handle.
 6. A power tool according to claim 1wherein the body is of generally cylindrical form and houses therein amotor for driving the shafts of both work holders the body being mountedupon a handle for rotation about an axis at right angles to the axis ofthe cylindrical body and the handle having fixed thereon a projectingguard means, the arrangement being that the body may be rotated through180* so as to bring one implement out of the region of protection of theguard means into an operating position whilst moving the other implementback into the region of protection of the guard means.
 7. A power toolAccording to claim 6 wherein the guard means comprises an arm fixed atone end to a handle adjacent where the body is mounted thereon said armextending radially outwardly from the handle and having its outer endcurved back to provide the guard for one or the other of the workimplements.
 8. A power tool according to claim 1 wherein the body is ofgenerally cylindrical form and houses a motor and gearing for drivingthe holders arranged in axial alignment, the body being mounted forrotation upon a handle about an axis at right angles to the axis of thecylindrical body and there being provided at each end of the body atwo-part guard comprising a first sleeve fixed to the body and a secondsleeve telescopically engaged with the first sleeve so as to be movablebetween a fully extended position in which it guards its associated workimplement and the retracted position in which it exposes the implement.9. A power tool according to claim 8 wherein each two-part guard has thesecond sleeve slidable telescopically within the first sleeve and springurged in the direction outwardly of the first sleeve, there being fixedto the handle of the tool, at the front thereof, a resilient lockingmember which projects through the wall of the outer sleeve and engagespart of the inner sleeve, of the guard which is in the front positionfor operation of its implement, so as to hold the inner sleeve in theretracted position.
 10. A power tool according to claim 9 wherein thesaid locking member comprises a nose at the free end of a resilient armthe upper end of which is fixed to the handle, the nose projectingthrough a circumferential slot in the outer sleeve and such slot beingwider in the direction transverse to the axis of the sleeve than thenose, whereby a small angular movement of the body from the operativeposition results in the said part of the inner sleeve moving out ofengagement with the nose to permit the inner sleeve to be spring urgedto its outer position.
 11. A power tool according to claim 10 wherein,at its rear side, the handle has fixed thereto a locking lug whichprojects through the aforesaid slot of the guard, the implement of whichis in the inoperative positon, and engages a part of the inner sleeve toprevent same from being moved inwardly in relation to the outer sleeve.12. A power tool according to claim 11 wherein the inner sleeve of eachguard has a finger piece on its wall projecting outwardly through anelongated slot in the outer sleeve whereby the inner sleeve can be movedmanually from its extended position to its retracted position.
 13. Apower tool according to claim 1 wherein two similar slots are providedon the underside of the body of the tool and the trigger has a partarranged so as to engage in one or other of the slots when the triggeris pressed to operate the motor, whereby relative movement between thebody and the handle when the motor is driven is prevented.
 14. A powertool according to claim 13 wherein each said slot has one side edgelonger than the other and an open mouth through which said part of thetrigger engages when it is pressed to operate the motor, and said partof the trigger being engaged also by the longer edge of the slot when itis in the released position so as to act as a stop defining theoperative position of the body whichever work implement is in use.